The invention relates to heat transfer plates for a plate heat exchanger functioning as an evaporator and/or condenser. The plates have a heat transfer range and peripheral openings for the heat transfer media, namely at least one product to be partially evaporated or condensed on the one hand, and a heating or cooling medium on the other hand. One group of the openings is allocated to one medium and one side of the plate, and another group of the openings is allocated to the other medium and the other side of the plate by appropriately placed seals.
Heat transfer plates of this type are stacked to form a packet, so that the product or the heating/cooling medium flows alternately in the spaces between the plates. The plates are known in a great variety of designs and profiles and are distinguished by a high heat transfer output due to the split flow.
Usually, the openings are arranged in the four corners of the plate, such that two diagonally opposite openings serve as the inlet opening and outlet opening for one medium, while the two other diagonally opposite openings are separated by seals from the first medium and are used for the flow of the second medium to the next space between the plates.
However, other positions for the openings in the plate are also already known. Thus, German Patent DE 32 20 774 of the present applicant describes a plate evaporator or condenser in which the plates have laterally protruding projections in those openings, so that continuous channels are produced. These channels are used especially for supplying heating steam. In addition, International application publication WO 01/90671 discloses a heat transfer plate which has two inlet openings closely adjacent to one another in the lower, middle area from which the medium first enters an intermediate chamber, so that the partial flows coming from the two inlet openings intermix. The medium then flows along the heat transfer area to the other plate edge into a common central outlet opening.